| Siwan | |
| Native Name: | सिवान |
| Native Name Lang: | hi |
| Settlement Type: | CD Block |
| Seat Type: | Headquarters |
| Seat: | Siwan |
| Pushpin Map: | Bihar |
| Pushpin Label Position: | right |
| Pushpin Map Caption: | Location in Bihar, India |
| Coordinates: | 26.2262°N 84.3453°W |
| Subdivision Type: | Country |
| Subdivision Name: |  India |
| Subdivision Type1: | State |
| Subdivision Name1: | Bihar |
| Subdivision Type2: | District |
| Subdivision Name2: | Siwan |
| Subdivision Type3: | Subdivision |
| Subdivision Name3: | Siwan |
| Governing Body: | Siwan Block |
| Unit Pref: | Metric |
| Area Total Km2: | 137.34 |
| Population Total: | 340983 |
| Population As Of: | 2011 |
| Population Density Km2: | auto |
| Demographics Type1: | Languages |
| Demographics1 Title1: | Official |
| Demographics1 Info1: | Bhojpuri, Hindi, Urdu, English |
| Timezone1: | IST |
| Utc Offset1: | +5:30 |
| Postal Code Type: | PIN |
| Area Code Type: | Telephone code |
| Blank1 Name Sec1: | Sex ratio |
Siwan community development block or simply Siwan Block (Hindi: सिवान सामुदायिक विकास खण्ड) is a Community development block in district of Siwan in Bihar state of India.
The total area of Siwan Block is 137.34km2 and total population of block is 340,983 (including rural area and urban city).[1] Siwan Nagar Parishad is the headquarter of the block.
Siwan block is divided into many Panchayats and a Municipality.
There is one Municipal council in Siwan district, in Siwan block categorised as Nagar Parishad.[2]
There are many Gram Panchayats in Siwan block:[3]